426 SKELETON OF THE FOWL. 



the lower border of the ischium. It forms a 

 very small part of the ventral border of the 

 acetabulum, in front of which it extends for- 

 wards as a blunt pre-pubic process. 



Behind the acetabulum, the pubes and 

 ischium are separated by the slit-like obturator 

 foramen, behind which the two bones are 

 fused for a short distance. The hinder end of 

 the pubes is thickened, and extends some dis- 

 tance beyond the ischium. 



D. The Hind-limb. 



In the bird's leg there is the same extensive fusion of 

 the bones which is characteristic of other parts of the skeleton. 

 There are no free tarsals, the proximal row having fused with 

 the tibia, and the distal row with the metatarsals. 



The position of the limb is the same as in the rabbit ; the 

 knee pointing forwards, and the preaxial border being internal 

 along the whole length of the limb. 



1. The thigh has only a single bone. 



i. The femur has a cylindrical slightly curved 

 shaft, and enlarged ends. The proximal end 

 is produced on its inner side into a rounded 

 head, articulating with the acetabulum. On 

 the outer or postaxial side of the head is an 

 irregular process, the great trochanter. Be- 

 tween this and the head, at the proximal 

 end of the bone, is the articular surface for 

 the anti-trochanter of the ilium. 



The distal end of the femur presents in 

 front a deeply grooved pulley-like surface for 

 the patella, a sesamoid bone in the tendon of 

 the extensor muscle of the leg : this surface is 

 bounded laterally by two prominent condylar 

 ridges, which articulate with the tibia ; the 

 outer or postaxial condyle having on its pos- 

 terior surface a deeply grooved facet for the 

 upper end of the fibula. 



